408 
THE MED I T E R R ANK A N NATURALIST 
calculated that a pound of matter falling 
from infinity would develop 82,840,000 
units of heat, and, therefore, that an annual 
meteoric fall equalling roo of the earth’s 
mass would maintain the heat observed. 
The linear contraction of the sun’s radius 
necessary to keep up the present radiation 
(allowing this to be 25 calorics per square 
metre per minute) is 156, 9 feet in a year, 
or nearly 30 miles in 1000 years. At this 
rate, it would require 7575 years for the 
sun to shrink one second of arc, this being 
the smallest angle measurable on the solar 
disc. 
A novel electroscope due to Mr. E. C. Ri- 
mington, an English electrician, is especial- 
ly interesting on account of its generation 
of light by a very small mechanical effort. 
A. T. shaped tube about five inches long, 
with about the bore of a spirit thermometer, 
and terminating in two bulls, has its air 
exhausted by an air-pump, and is them 
rotated between the finger and thumb, or by 
a small motor. On bringing a rubbed 
ebonite or glass rod near, a set of double 
fan-shaped images of light appears in the 
tube. 
Iff is odd to think of wild camels roam- 
ing about in Europe. Yet a recent traveler 
in Spain has proved Their existence, the 
animals being evidently descendants of 
some which were introduced from the 
Canaries in 1833, and for some years used 
as beasts of burden in the province of Cadiz. 
A- English chemist points out that the 
air held by sea-water increases in proportion 
with the depth, and that it is quite possible 
that the ocean may hide an atmosphere 
nearly equal to that above its surface. 
VJ^RITING on the subject of baldness, Dr. 
W. Joseph Syson remarks that it is much 
more common in men than in women, and 
he considers the causes to be insufficient 
exposure of the hair, influence of heredity 
excessive mental work and great anxiety, 
venereal and alcoholic excesses, constant 
washing, and want of pomade. Just how 
much is due to each cause cannot readily 
be estimated, The treatment recommended 
is the use of a light head-covering, to be 
worm as little as possible; washing only 
about once a week, with avoidance of much 
brushing; and the occasional application of 
some form of simple grease or oil. 
iHE City of Mexico occupies a peculiar 
position, being at an elevation of 7500 feet 
above sea-level and yet at the bottom of a 
deep valley with no natural outlet for 
drainage. The valley contains six lakes, 
which have an average total area of 200 
square miles. The height of the water va- 
ries greatly, but is usually greater than 
that of most of the ground in the city, 
whose sewage can be disposed of only by 
pumping into the lakes. As a relief from 
inundations, a cutting 13 miles long through 
the hills was made by the Spaniards, who 
finished it in 1789 after nearly two centu- 
ries of work. Thi,s proved insufficient, but 
nothing further seems to have been attemp- 
ted until about 25 years ago, when the 
Mexican government caused some French 
engineers to commence a tunnel to lead the 
O 
water through intervening high ground to 
the cutting. These engineers deepened the 
cutting, completed about a mile of the tun- 
nel at the outlet end, and commenced 25 
shafts. In 1888 the contract for finishing 
the undertaking was let to two British 
